And on Wednesday afternoon, an accident involving a small pickup truck and a Downeast Transportation bus became the latest incident that resulted in a traffic jam as vehicular travel on and off Mount Desert Island ground to a halt for hours.

Stopped cars on routes 3 and 102 stretched for miles Wednesday evening from the accident scene, located directly in front of Trenton Flooring & Furniture on Route 3, as motorists waited for response personnel to clear the roadway. For nearly seven hours, cars and trucks sat motionless while the pickup and bus blocked the road between Route 230 and the MDI causeway.

The section of Route 3 between the end of Route 230 in Trenton and where routes 102 and 198 branch off at the head of the island is a little more than a mile long and is the only road that connects MDI and its 10,000 or so residents to the rest of Maine. In the summer, thousands of tourists join the daily flow of MDI residents, seasonal tourism industry workers and hundreds of Jackson Laboratory employees that drive across the causeway every day.

Wednesday’s accident occurred around 3:30 p.m., right around the time that many Jackson Lab employees were finishing up work for the day.

Traffic initially was allowed to pass the damaged vehicles, but that changed when firefighters realized the fuel on the propane-powered bus was leaking.

Any slight spark could cause a dangerous explosion, officials feared, so they shut down the road and trained a jet of water from a fire hose on the area where the front end of the pickup remained stuck in the left side of the bus. Unable to stop the leak, they decided to let all the propane escape out of the fuel tank before they moved the vehicles.

More than six hours later, the propane was gone, the damaged vehicles moved, and the road was opened back up.

According to Hancock County Sheriff’s Deputy Chris Sargent, the accident happened when the bus pulled out of a parking lot driveway onto Route 3 in front of the pickup. The pickup truck could not stop in time, Sargent said.

“The truck really had nowhere to go,” the deputy said.

The pickup driver complained of back and knee pain after the collision, Sargent said, but did not sustain any apparent serious injuries. The bus driver was unharmed, he added.

Paul Murphy, general manager for Downeast Transportation, said Thursday that at the time of the accident, the bus was being used for a routine paid passenger service between Ellsworth and Bar Harbor. The bus is painted with the Island Explorer logo, he said, but that free seasonal service on and around MDI does not start until June 23. Downeast Transportation is the operator of the Island Explorer system.

Eleven passengers were on board the bus when it turned out of a former hotel property toward Bar Harbor and was hit by the truck, according to Murphy. Three of those passengers were taken to Maine Coast Memorial Hospital in Ellsworth, where they were treated for minor injuries and then released, he said.

Murphy said he understands how “painful” it is for MDI area residents when Route 3 near the head of the island is shut down.

“We sincerely regret that,” Murphy said.

He said that when any Downeast Transportation bus is involved in an accident, the safety of passengers, staff, the public and responding firefighters is a primary concern.

“Better that we are talking about a huge inconvenience than a loss of life,” Murphy said.

Murphy said he does not question how Wednesday’s accident was handled by response personnel, but that there might be ways going forward to improve response capabilities to Downeast Transportation or Island Explorer bus accidents. In the past, Downeast Transportation has donated buses to the local fire department for training purposes, he said.

No such arrangements have been made yet, he said, but Downeast Transportation would be happy to host a workshop in Trenton in which a trained technician from the bus manufacturer would discuss with local firefighters how the bus’s propane power and storage systems work.

“We will be picking this apart with a fine-toothed comb and I am sure we are not alone in that,” Murphy said.

Nate Young, police chief in Bar Harbor, said his department got many calls Wednesday evening, even though the Bar Harbor police and fire departments had no control over what was happening at the accident scene.

Young said he is curious if there may have been a way to allow traffic to move along Route 3 while first responders dealt with the accident. Young said he intends to request that MDI-area public safety officials meet with Andrew Sankey, the head of the county’s emergency management agency, to discuss how such incidents are handled.

“The island community needs to get a better understanding of what’s going to happen” in similar situations in the future, Young said.

Initial attempts Thursday to contact Sankey and Trenton Fire Chief Richard Gray were unsuccessful.